Orthotic devices and appliances commonly referred to as “orthotics,” are known in the prior art and have been utilized for many years by orthotists (a maker and fitter of orthotics), physical therapists, and occupational therapists to protect an injured or surgically repaired knee joint, or a weakened one caused by a neurological disability. Knee orthotics are also used to assist in the rehabilitation of a patient's knee joint and the associated limbs or adjacent skeletal parts of the patient's body related to knee instability.
Webster's New College Dictionary defines “orthotics” as a branch of mechanical medical science that deals with the support and bracing of weak or ineffective joints or muscles. The word “ortho” actually comes from Greek and means “to straighten.” Orthotics are used to support and straighten the effected joint and assist to correct normal human function as closely as possible. Orthotics used as limb braces have typically been designed to support and protect the joint that is associated with knee injury or post surgical use, and for alleviating pain associated with joint movement at the particular location being treated.
Knee laxity, due to ligament injury, can cause significant instability to the knee joint thereby predisposing the joint to further instability and more serious injury. The medial collateral ligament (MCL) and lateral collateral ligament (LCL) provide side to side stability of the knee joint. Injury to the MCL or LCL can result in lateral instability of the knee.
The anterior cruciate ligament (ACL) is responsible for controlling the forward glide of the tibia in relation to the femur. This movement is called “anterior tibial translation.” The ACL, in combination with the other ligaments, of a healthy knee joint restrict the rotation or twisting of the knee. Injury to the ACL can result in rotational and anterior instability of the knee.
The posterior cruciate ligament (PCL) is the primary restraint to post translation of the tibia on the femur and acts as a secondary restraint to varus/valgus movements and external rotation. Injury to the PCL can result in posterior instability of the knee whereby the patient feels that the knee can “pop-out” of place. PCL injuries are the least common form of knee instability injury.
An injury or tear of any one of the aforementioned ligament predisposes the knee joint to secondary injuries to the other ligaments, as well as to the meniscus and articular cartilage of the knee. Approximately 50% of all ACL injuries occur in combination with damage to the meniscus, articular cartilage or other ligaments. Protecting and supporting a weakened knee joint after injury or pre or post-operatively, from the medial, lateral or rotational forces exerted upon the knee during walking, squatting and other movements is the primary purpose of a knee orthosis device for knee instability.
Patients who have suffered a traumatic brain injury, stroke or who have Cerebral Palsy, MS or other neurological disabilities that results in muscle weakness, a loss of proprioception and poor balance may also require a knee orthosis to protect and stabilize the knee joint from injury and to allow for safe ambulation.
It is also known that ligaments become more compliant with age, which can also lead to significant knee laxity. Knee laxity may be broadly defined as abnormal displacement or rotation of the tibia with respect to the femur. In the unloaded state, knee stability is provided by the ligaments, joint capsule and other soft tissues. In the loaded state, the interactions between ligaments, other soft tissues, condylar geometry, and tibiofemoral contact forces generated by muscle activity and gravitational forces maintain knee stability. Joint laxity reflects an impairment of the passive restraint system for which muscle activity may or may not compensate. Knee joint laxity may adversely affect joint mechanics which can lead to an unstable knee joint and abnormalities in gait kinetics.
Knee instability, whether due to ligament injury, surgery or muscle weakness in the muscles supporting the knee joint during locomotion and other activities may require a supportive and protective knee orthosis device to prevent secondary damage to the knee resulting in more serious injury. A knee orthosis device used to treat knee instability must provide medial, lateral and rotational support of the knee during walking and other activities to adequately support and protect the knee joint.
The prior art includes a multiplicity of various knee brace designs. However, most knee instability brace designs include a rigid anterior thigh cuff, a rigid anterior shin cuff, a rigid medial upright with a unicentric or polycentric hinge, a lateral upright with a unicentric or polycentric hinge, a strapping system, and condyle pads or another stabilizing force system at mid knee joint on both sides. Examples of such devices can be seen in U.S. Pat. No. 4,493,316 to Reed et al., U.S. Pat. No. 4,856,501 to Castillo et al., US Published Application No. 2002/0183674 to Castillo and US Published Application No. 2007/0066923 to Sreeramagiri. Other knee instability or ligament braces have a rigid anterior thigh cuff, a rigid posterior calf cuff, rigid medial and lateral uprights, condyle pads, a strapping system and unicentric or polycentric hinges such as the “Donjoy Defiance” brace. Still other knee instability knee braces have a rigid posterior thigh cuff, a rigid anterior shin cuff, rigid medial and lateral uprights with polycentric hinges, condyle pads and a strapping system such as the “Donjoy 4Titude” brace.
Therefore, what is clearly seen in the prior art of all knee laxity or ligament braces are rigid structures having a top structure of the brace constructed as one uniform part (thigh cuff and upper portion of the upright), which then connects at the hinge to the lower rigid structure of the brace (lower uprights and shin or calf cuff). These rigid structures, which typically employ static straps, may immobilize the knee joint. However, they lack the ability to flex and conform to the motions of a patient's muscular areas around the knee joint when the patient is walking, squatting or rising from a sitting position, let alone exerting a more rigorous motion such as running, dancing or performing any other motion required from someone engaged in a sport activity. Simply put, the prior art braces lack any “dynamic conformability.” In other words, the prior art braces and their static straps do not conform to the ever changing, and often unpredictable, dynamics of the knee joint and the surrounding muscles there around. The static nature of the strapping seen in the prior art not only prohibits, but discourages expansion, which then would permit a return to a relaxed state after the strap is “unloaded.” That is because all current prior art braces that employ static strapping use such strapping to hold the brace in place and to mitigate brace migration. And for these reasons, the prior art knee laxity and/or ligament braces are inadequate and are in great need of improvement.
Another troubling problem with the rigid structure of existing knee instability brace designs is that the braces can alter normal gait biomechanics. Because they are rigid in design, and because of the dynamic motion of the knee and leg when walking, squatting, running, etc., the braces are prone to slippage and brace migration. Simply put, the prior art braces do not conform to the constantly changing shape of the leg above and below the knee joint during motion. Further, the greater the intensity of the body motion, the more likely brace slippage and migration will occur.
The most recent knee ligament brace innovations involve condyle pad construction or strapping systems intended to keep the brace in place during normal activities. These new components have been added to the rigid structure of the brace (uprights and cuffs). Such “improvements” can be seen in U.S. Pat. No. 7,198,610 to Ingimundarson, et al. and PCT Application Publication No. WO 2007/109112, also to Ingimundarson, et al. In spite of these innovations and supposed improvements, brace migration continues to be one of the most common complaints among brace users.
Brace migration during brace use can be extremely problematic for the patient. If the condyle pads, which are also static in the prior art, become misaligned, optimal brace protection of the knee joint is compromised. As the brace slips down, the axis of the brace and the axis of the knee joint will not align correctly, and this can place unwanted forces on the knee joint, which affect gait and the normal biomechanics of walking and other activities. Patients can become noncompliant and will thus avoid wearing their brace because it is extremely inconvenient to constantly readjust the brace during certain activities. A brace that is designed and engineered to not slip or migrate with significant activity would be a significant improvement over existing knee instability braces and is a feature that is clearly needed in knee orthosis devices.
Further, many of the existing knee braces utilize range of motion stops (flexion and/or extension) that must be manually inserted into the hinge assembly with tools to set the desired degrees of flexion and extension limits prescribed by the physician. This continues to be a problem, which clearly needs improvement thereupon.
In addition, no knee instability or knee ligament braces, which are currently available, are designed to maintain or strengthen the musculature of the leg, post injury or post surgery and during brace use. Due to the fact that the gait of a patient having significant knee laxity or a knee ligament injury is usually altered as a means to avoid pain and re-injury of the knee joint, and further that known prior art rigid knee braces contribute to an abnormal and altered gait, full use of the leg muscles is significantly reduced, which then leads to significant muscle atrophy. It is non uncommon for a patient who suffers a knee ligament injury to lose muscle mass in the thigh area of the leg in as little as eight to fourteen days of limited activity. Often, measurable loss of thigh circumference, a common means for measuring the loss of muscle mass, can be one to three inches of thigh circumference.
The present invention is uniquely designed to correct for alterations in gait by providing significant knee support, correcting knee joint alignment, and through the use of a dynamic swing assist, maintain an as normal as possible heel to toe walking pattern. Normal heel to toe walking is critical to initiate the firing of all of the muscles in the quadriceps in the correct firing pattern, which is necessary to maintain normal muscle mass and muscle strength. By correcting abnormal gait patterns and facilitating a heel to toe walking pattern, the present and novel invention provides rehabilitative benefits to the patient that are not available with existing prior art knee ligament braces. By correcting gait and facilitating a heel to toe walking pattern, muscle use is maintained, thereby diminishing the potential for the loss of muscle mass and strength. This is a significant benefit over other knee ligament braces of the prior art, as it can lead to significant reduction in the rehabilitation necessary to re-strengthen the leg musculature post injury or surgery.
What is therefore needed is a complete knee laxity brace that can protect and support the knee medially, laterally and rotationally, provide a swing-assist function for extension, provide a corrective and therapeutic force that can return the patient to a more true normal gait (heel-to-toe strike while walking) to prevent abnormal rotation of the knee joint, all the while recruiting atrophied muscles to work again and to rehabilitate themselves so that the patient can once again return to the closest possible “normal” condition based upon the specific progression of their respective knee laxity condition. The goal for any advancement in the art should be an improvement from “abnormal gait” to a more biomechanically correct normal gait kinetic, believed to be a significant factor in reducing the rehabilitation necessary to allow for unaided ambulation. A truly rehabilitative knee brace would maintain muscle strength or strengthen the leg musculature over time using dynamic adjustable components such that a reduction of pain and rehabilitation time would be both evident and realized. Such a described and needed brace currently does not exist in anywhere in the prior art. Simply put, an improved knee laxity or ligament brace should be used with patients who can begin “brace therapy” immediately after injury, at the time before a surgical procedure is be performed on the knee joint and immediately post surgery to effectively improve the condition of the knee joint with routine brace use while providing support and protection of the joint.